Novel tetrazole-functionalized ion exchanger for weak cation-exchange chromatography of proteins

A new type of weak cation exchanger, tetrazole-functionalized silica, was developed for bioseparation. It was prepared conveniently by modifying silica gel initially with gamma-glycidoxypropyltrimethoxysilane, then with 3-hydroxypropionitrile and finally with ammonium-catalyzed (3+2) azide-nitrile cycloaddition, which is an element of click chemistry. The prepared stationary phase was characterized and evaluated for its separation performance, protein retention behavior, loading capacity, protein recovery and chemical stability. The results show that the stationary phase developed has excellent performance for protein separations with high mass recoveries, and has long-term stability. Some remarkable differences were observed between this new exchanger and a carboxylic methyl-functionalized ion exchanger, which is typically used in weak cation-exchange chromatography of proteins. The obtained column was also used for the purification of lysozyme from chicken egg white, and the purity and specific bioactivity of the obtained lysozyme were about 90% and 67 IU/mg, respectively.     

牦牛角成分的薄层色谱法分离研究

牦牛角成分的薄层色谱法分离研究雷根虎,曹永民（西北大学化学系西安７１００６９）关键词薄层色谱法,氨基酸,牦牛角１引言牦牛产于我国的青藏高原,迄今人们已对其乳汁、胆汁、骨、甲状腺、血液等做了系统的分析［１］,然而对于其角的分析至今未见报道。为了合理地开...     

Stochastic resonance in a harmonic oscillator with damping trichotomous noise

In this paper, the phenomenon of stochastic resonance (SR) in a prototype fluctuating damping harmonic oscillator with trichotomous Markovian noise is investigated. The exact expression of output amplitude gain has been calculated using the well-known Shapiro–Loginov formula. The phenomenon of SR has been found in a broad sense—that is, the non-monotonic behavior of output amplitude gain as a function of noise parameters. Then the influences of noise amplitude, noise switching rate, and noise flatness on the output amplitude gain have also been discussed. Finally, the reverse resonance phenomenon has been presented.     

New alpha-amino phenylalanine tetrazole ligand for immobilized metal affinity chromatography of proteins

A new chelating compound has been developed for use in the immobilized metal affinity chromatographic (IMAC) separation of proteins. The bidentate ligand, alpha-amino phenylalanine tetrazole, 4, was synthesized via a five-step synthesis from N-fluorenylmethoxycarbonyl phenylalanine and then immobilized onto silica through the epoxide coupling procedure. The binding behavior of the resulting IMAC sorbent, following chelation with Zn2+ to a density of 183 micromol Zn2+ ions/g silica, was characterized by the retention of proteins in the pH range of 5.0-8.0, and by the adsorption behavior of lysozyme with frontal chromatography at pH 6.0 and 8.0. The prepared column showed the separation ability to four test proteins and the retention time of these proteins increased with an increase in pH. From the derived isotherms, the adsorption capacity, qm, for the binding of lysozyme to immobilized Zn2+-alpha-amino phenylalanine tetrazole-silica was found to be 1.21 micromol/g at pH 6.0 and 1.20 micromol/g sorbent at pH 8.0, respectively, whilst the dissociation constants KD at these pH values were 5.22x10(-6) and 3.49x10(-6) M, respectively, indicating that the lysozyme was retained more stable under alkaline conditions, although the binding capacity in terms of micromole protein per gram sorbent remained essentially unchanged.     

固相萃取-高效液相色谱法测定辣椒中甲基硫菌灵的残留量

甲基硫菌灵的化学名称为1,2-双(3-甲氧羰基-2-硫脲基)-苯,是内吸性杀菌剂,对蔬菜、水果、麦类等的真菌病害有良好的防治效果。它在生物体内和环境中不稳定,因而增加了测定的难度。已报道的分析方法有生物测定法、紫外分光光度法、气相色谱法和液相色谱法。这些方法的样品前处理繁琐,有机溶剂用量多,分析时间长。本文采用中性氧化铝固相萃取小柱净化样品,     

流动相组成和温度对衍生化β-环糊精键合固定相拆分四种仲醇消旋体的影响

采用3,5-二甲苯基异氰酸酯衍生化β-环糊精键合固定相,以正己烷-脂肪醇为流动相,研究了脂肪醇结构及其浓度、柱温对2-苯基环己醇、2-萘基环己醇、4-三氟甲基-2-苯基环己醇以及3-(1-羟乙基)香豆素等四种仲醇手性拆分行为的影响.当流动相中醇的摩尔浓度相同时,异构体容量因子随脂肪醇碳链的增长而减小;柱温升高,异构体容量因子减小,而分离因子增大.用溶质的计量置换保留模型(SDM-R)和热力学理论对此现象进行了解释.     

Use of Frontal Chromatography to Measure the Binding Interaction of Berberine Chloride with Bovine Serum Albumin

There is much interest in the interactions between the active constituents of traditional Chinese medicine and biomolecules. By use of frontal analysis on an affinity column we have examined the binding interaction of berberine chloride (BC), a major active constituent of coptis, with bovine serum albumin (BSA) in 40 mM phosphate buffer, pH 7.0. Adsorption of BC on immobilized BSA was in accordance with the Langmuir isotherm, suggesting BC is binding to a single type of site on the immobilized BSA. The binding constant was 4.79 × 10⁴ L mol⁻¹ at 30 °C, less than the value of 6.61 × 10⁴ L mol⁻¹ obtained by fluorescence spectroscopy under the same buffer and temperature conditions. The effects of temperature on the retention, binding constant, and active binding sites, and on the percentage protein binding of BC, were also investigated. Thermodynamic measurements indicated that the increase in entropy was an important process promoting the interaction between BC and BSA.

     

Use of Frontal Chromatography to Measure the Binding Interaction of Berberine Chloride with Bovine Serum Albumin

There is much interest in the interactions between the active constituents of traditional Chinese medicine and biomolecules. By use of frontal analysis on an affinity column we have examined the binding interaction of berberine chloride (BC), a major active constituent of coptis, with bovine serum albumin (BSA) in 40 mM phosphate buffer, pH 7.0. Adsorption of BC on immobilized BSA was in accordance with the Langmuir isotherm, suggesting BC is binding to a single type of site on the immobilized BSA. The binding constant was 4.79 × 10⁴ L mol^?1 at 30 °C, less than the value of 6.61 × 10⁴ L mol^?1 obtained by fluorescence spectroscopy under the same buffer and temperature conditions. The effects of temperature on the retention, binding constant, and active binding sites, and on the percentage protein binding of BC, were also investigated. Thermodynamic measurements indicated that the increase in entropy was an important process promoting the interaction between BC and BSA.     

磷酸锡的离子交换性质(Ⅲ)——四十四种金属离子的薄层层析

本文用磷酸锡无机离子交换剂制成薄层板,不另加粘合剂,以DMSOHNO₃为混合溶剂系统对四十四种金属离子的薄层层析行为进行了研究。实验结果表明:在混合溶剂系统中,增加硝酸的浓度,磷酸锡交换剂中的交换基电离度降低,许多金属离子的比移值有所增加;当以DMSO-H₂(1:1)为溶剂,除Hg²⁺,Cd²⁺,Cr³⁺(或Cr⁶⁺和贵金属离子外,其它金属离子的比移位接近于零。故选择适当比例的DMSO-HNO₃和DMSO-H₂O为混合溶剂系统,利用磷酸锡对某些金属离子的选择性,可使许多金属离子相互分离。如:Hg²⁺与Pb²⁺,Cd²⁺与Pb²⁺,Hg²⁺与Hg₂²⁺,Pb²⁺与Zn²⁺,Hg²⁺与As³⁺等的分离是成功的。这些离子对环境保护中微量组分的分离和富集具有一定的使用价值。     

前沿色谱法对盐酸小檗碱和固定化牛血清白蛋白结合作用的研究

盐酸小檗碱(BC)是黄连的主要有效成分,它具有抗菌消炎等多种作用。采用前沿色谱法测定了不同温度下BC与固定化牛血清白蛋白(BSA)的结合常数K和结合率PPB、BC的保留因子k、BC在色谱柱上活性位点的物质的量mL,以及BC与BSA结合过程中的热力学参数。在温度为30 ℃时,BC与BSA的结合常数为4.79×104 L/mol。K、k和mL均随温度的升高而降低,其中以mL的变化程度最为显著,表明k的降低是由于K与mL共同作用的结果。而BSA分子构象变化可能是mL降低的主要原因。热力学分析结果表明:BC和BSA之间的作用力以静电作用力为主。